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Treatment of the Siirt-Madenk÷y Ores by Flotation

Sep 13, 2010

By F. Dai

Due to difficulties associated with gripping in direct tension, indirect methods are commonly used to measure rock tensile strength. In this work, we adopt an innovative indirect tensile test method: Semi-Circular Bend (SCB) to measure the tensile/flexural strength of Laurentian granite (LG). The static tests are carried out with a servo-controlled material testing machine and the dynamic tests are conduced with a Split Hopkinson Pressure Bar (SHPB) system. Pulse shaping technique is adopted to achieve dynamic force equilibrium in SHPB to facilitate data regression. Finite element method is used to relate the failure load to the tensile strength. Strong rate dependence of the tensile strength is observed. The flexural strength is higher than the tensile strength measured using Brazilian Disc (BD). This difference is rationalized using the non-local theory. To further validate the method, a coupled Finite element/Discrete element method (Fem/Dem) in conjunction with the smeared crack model is utilized to simulate the fracture process during dynamic SCB tests. The resulting fracture patterns are qualitatively consistent with those from recovered samples. Both the experimental and numerical methods have validated the results and this new method is readily to be used for other rocks and other brittle materials.

May 1, 2009

By A. du Plessis

The study summarized in this paper focused on expanding existing South African mine closure cost calculation models to provide a new model that incorporates risks, which could have an effect on the closure costs during the life cycle of the mine. This research is important because currently there are a number of mines that do not have sufficient financial provision to close and rehabilitate the mines. The magnitude of the lack of funds could be reduced or eliminated if the closure cost calculation is done in a more risk-orientated manner. The model consists of an expansion of existing closure cost calculation models, by applying the Monte Carlo risk simulation technique to model influences of external and internal changes affecting closure costs. It is shown that the proposed risk-based model provides a way to understand better the implications of uncertainty on the closure costs.

Jan 1, 2006

The Golden Cross mine commenced production in December 1991. Both open pit and underground mines produce 1000 tonnes of ore per day. Mining techniques are discussed along with results and variations to proposed methods of extracting the ore.

Jan 1, 1992

By Shaw-Shong Liew

This paper presents the design concept using floating piles to support 2500Ton oil storage tanks on a very soft alluvial clayey soil of about 40m thick in Riau Province of Sumatra, Indonesia. The floating piles of various penetration lengths were designed to support seven numbers of such storage tanks seating on a 20m diameter and 500mm thick reinforced concrete (RC) circular raft. The pile points have been strategically located at the RC raft. Varying pile penetration lengths have been designed to minimize the angular distortion of the thin RC raft and the out-of-plane deflection at the tank edge. Vibrating wire strain gauges were installed at different levels inside the ø350mm prestressed reinforced concrete piles to measure the load transfer profile during the static load tests and water-loading test. The installation and interpretation of the instrumentation are described and discussed. Boreholes, in-situ tests like piezocones, vane shear tests and standard penetration tests, and laboratory testing were carried out to obtain geotechnical parameters for the pile designs. Static load tests were also carried out on the spun piles of varying lengths of 24m, 30m and 36m respectively. It has been demonstrated that the floating pile system can be a cost effective design to support heavy structures on very soft compressible deposits with satisfactory performance. Finally, the design concept validated with the results of instrumentation is discussed.

Jan 1, 2002

Inhibition of Bubble Coalescence by Salts and Sugars

Sep 13, 2010

By A. Thoraval, K. B. Slimane, O. Ozanam

The REP experiment is part of the research programme conducted by Andra to investigate the possibility of reversible radwaste disposal in a Jurassic (Callovo-Oxfordian) argillite formation at the Meuse/Haute-Marne underground laboratory site in northeastern France. The experiment focuses on the hydromechanical response of the formation to sinking the laboratory access shaft. Modelling of boreholes and shaft sinking operations has helped to optimise measurement point locations based on initial stress tensor anisotropy, while minimising interaction between instrument boreholes. Analyses were made of model sensitivity to intrinsic rock characteristics, hydromechanical coupling properties and sensor installation procedures. L’expérimentation REP fait partie du programme de recherche pluridisciplinaire engagé par l’Andra pour étudier la possibilité d’un stockage réversible des déchets radioactifs dans la formation Callovo-Oxfordienne des argilites du site de Meuse/Haute-Marne (Commune de Bure - France). Cette expérimentation permettra d’étudier la REponse hydromécanique de la formation aux sollicitations engendrées par le fonçage du Puits d’accès du laboratoire souterrain de recherche. Afin d’optimiser le positionnement des points de mesures, compte tenu de l’anisotropie du tenseur des contraintes initiales, et de minimiser les interactions entre les forages d’instrumentation, des modélisations des forages et du creusement du puits ont été conduites. Des analyses de sensibilité aux caractéristiques intrinsèques de la roche, aux propriétés de couplage HM et aux protocoles d’installation des capteurs ont été faites. Die REP-Untersuchung ist Teil des multidisziplinären Forschungsprogramms, das die ANDRA im Callovo-Oxfordian-Tonstein in situ am Standort Meuse/Haute Marne (Gemeinde Bure – Frankreich) im Hinblick auf eine Eignung zur reversiblen Lagerung radioaktiver Abfälle durchführt. Dabei soll das hydro-mechanische Verhalten der Formation auf die Beanspruchungen, die durch das Abteufen des Zugangsschachts zum Untertage-Forschungslabor erzeugt werden, untersucht werden. Zur optimalen Positionierung der Messpunkte unter Berücksichtigung der Anisotropie des Tensors der Ausgangsspannungen und zur Minimierung der gegenseitigen Beeinflussung der Instrumentierbohrungen wurden ein Schachtabteuf- und Bohrmodelle entwickelt. Zur Untersuchung der inhärenten Eigenschaften des Gesteins, des gekoppelten HM-Verhaltens und der Installationsprotokolle der Messsonden wurden Sensibilitätsanalysen durchgeführt.

Jan 1, 2003

Roasting of a Copper Sulfide Concentrate

Sep 13, 2010

By Dana C. Reinke

Water well drillers are exposed to high levels of noise while working. NIOSH researchers have found that water well drillers are exposed to levels above 85dB (A) while performing certain tasks during a typical drilling job. Noise levels consistently over 85dB (A) during an 8–hour work shift are hazardous and can lead to hearing loss in workers. Finding ways to reduce noise exposure is difficult because of many factors. The work environment is constantly changing due to the location of jobs and environmental factors. The types of drill rigs required for drilling are expensive. Equipment can range from new to used (10 to 30+ years old). Drillers and owners can work together to prevent noise–induced hearing loss, and measures can be taken to reduce exposure to hazardous noise.[ ] Preventing hearing loss occurs through three stages. The first stage is removing noise from the source (i.e., drill rig). Various parts of a drill rig create noise besides the drilling rod. NIOSH researchers have examined noise levels of drill rigs. Some of the loudest parts of the drill rig include the compressor, engine, and cooling fan (Fig. 1). While removing the noise source from a worksite is ideal, the process would be expensive and difficult.[ ]

Jan 9, 2005

By S. Kouniali

Experience with knowledge-based systems for Layout planning and roadway support dimensioning is on hand in European coal mining since 1985. The systems SOUT (support choice and dimensioning, 1989), SOUT 2, PLANANK (planning of bolt-support), EXOS (layout planning diagnosis. 1994), Sout 3 (1995) have been developed in close cooperation by CdF1. INERIS2. EMN3 (France) and RAG 4, DMT5, TH - Aachen6 (Germany); ISLSP (Integrated Software for Layout and support planning) development is in progress (completion scheduled for July 1996). This new software technology in combination with conventional programming systems. numerical models and existing databases turned out to be suited for setting-up an intelligent decision aid for layout and roadway support planning. The system enhances reliability of planning and optimises the safety-to-cost ratio for ? deformation forecast for roadways in seam and surrounding rocks, consideration of the general position of the roadway in the rock mass (zones of increased pressure, position of operating and mined panels). ? support dimensioning ? yielding arches, rigid arches, porch sets, rigid rings, yielding rings and bolting / shotcreting for drifts ? yielding arches, rigid arches and porch sets for roadways in seam ? bolt support for gateroads (assessment of exclusion criteria and calculation of the bolting pattern) ? bolting of face-end zones (feasibility and safety assessment, stability guarantee).

Jan 1, 1996

In this study, a 3D model of the shovel motion based multi-body system dynamics in the Automatic Dynamic Analysis of Mechanical Systems (ADAMS) environment was developed. The kinematics model of the shovel was modeled as a multi-body system, which comprises the lower, upper, and the attachment mechanisms. The Euler-Lagrangian equations were employed as the computational framework to describe the dynamic behavior of the model. A virtual prototype of the shovel was built in the ADAMS software environment. This environment allows the visualization of a 3D motion of the general mechanical system and the prediction of interference of the moving components of the shovel. The numerical analysis and animation of digging, swinging and dumping motions for the shovel were performed. The superimposed display of the deployment for the shovel in three phases allows a detailed examination of the dynamic interference among assembly components. This research provides a solid foundation for further shovel dynamics performance studies. Keywords: Shovel, Spatial Kinematics, Virtual Prototype, Visualization

Jan 1, 2009

By N. R. Williams

Black Mountain, a polymetallic base metal mine located in the Northern Cape territory of South Africa has been blessed with high grade economic ore for many years. Now that the Broken Hill orebody is nearing the end of its life, a lower grade orebody (Swartberg) is being exploited to supplement production from Broken Hill. In addition, ore from stopes in the upper levels of the Broken Hill orebody is considerably tarnished (oxidized). As a natural result, the remaining ore contains a higher percentage of magnetite, pyrrhotite and pyrite than in earlier years. Bismuth, cadmium and cobalt also occur in the ore in higher quantities. The life of the mine has been lengthened with the discovery of further deeper-lying ore reserves extending from the Broken Hill orebody suitably called the Deeps section. However, to bridge the gap between development of the new reserve and the exhaustion of the old reserve, these lower grade and tarnished (oxidized) ores have to be treated. The mine has had reasonable success in identifying unfavourable or problematic ore types and stockpiling them separately to blend in small quantities with more favourable ore. Bench and plant scale tests have aided identification of the various ore types and significant improvements in flotation metallurgical results have been seen. Copper, lead and zinc metal occur as sulphides in the ore. The mill consists of a differential and sequential flotation process that extracts copper concentrate, lead concentrate and zinc concentrate respectively with silver metal recovered in the copper and lead concentrates. This paper describes the ore blending strategy employed at the mine to maximize the econo-metallurgical efficiency of the operation.

Jan 1, 2001

The achievement of high availability of the Grey River Gold Mining Limited's alluvial gold dredge is a tortuous task which will rely upon the dedication of all staff employed at Grey River Gold Mining Limited (GRGML). The persistent adoption of new technology and better operating procedures, combined with a strong commitment to preventative and predictive maintenance, is necessary. The Grey River Gold Mining Limited alluvial gold dredge is operating in a relatively low grade alluvial gold deposit and hence relies on a high throughput of ore to be profitable. To achieve the required high material throughput the dredge incorporates an overburden removal system which operates simultaneously with a conventional bucketline system.   The overburden system incorporates a cutter wheel and suction pump configuration which is dedicated to removing the low grade (5 mg gold/m3 gravel) overburden. The bucketline conveys the richer grade payzone gravels (up to 890 mg/m3 gravel) to the recovery plant mounted onboard the dredge. The horizon for the overburden system approximates 15 m and the payzone terminates at the interface of the old man rock and the alluvial gravels at a variable depth averaging 22 m.   From a mechanical engineering perspective the dredge is a machine comprised of two materials handling systems which are controlled by Operations Staff and electronic process control systems.   The availability of such a materials handling system is a function of four variables: 1. The environment that the machine operates in. 2. The ability of the people operating the machine. 3. The design of the mechanisms, the configuration that they are grouped in and the effectiveness of the process control systems which control the mechanisms. 4. The procedures utilised to predict the performance of the machines and the skill of staff to analyse that data and carry out effective maintenance.

Jan 1, 1989

The unpaved road network on a surface mine is extensive, comprising numerous roads of varying construction and material qualities with highly variable traffic volumes. Existing haul road maintenance management systems (MMS) work well for predictable traffic volumes, but for complex mine road networks, the MMS becomes onerous. This results in sub-optimal road maintenance strategies with the attendant increase in total road-user costs and reduction in service. A real-time maintenance management system was thus sought to overcome the deficiencies of existing MMS for mine roads. Since most large mines operate trucks with on-board diagnostic data collation, linked through a centralized communication and GPS backbone, it was proposed that road condition could be monitored on a real-time basis through on-board vibration signature analysis. The aim of this paper is to present the development of a real-time mine haul road maintenance management system. Following are view of mine road maintenance practices, the real-time system architecture is introduced and the results of a field trial of on-board vibration signature assessment is presented. The trial results are discussed in the light of road defect signature recognition, analysis, signature repeatability and system limitations. This approach has applicability to other situations such as a network of district roads, subject to an analysis of the economic feasibility. The paper concludes that modern technology has the potential to apply maintenance as and where needed with possible reductions in authority cost and an improvement in service provided for the road user.

Jan 1, 2003

By Holmes R. J, Miles J. G

An on-stream shale detector has been developed that is suitable for use on conveyor belts carrying iron ore of up to 200 mm particle size. The shale is distinguished from high-grade iron ore by means of the substantially greater total natural gamma-ray activity (400-3000 keV) of the shale, which is due to the presence of uranium (214Bi), thorium (208TI) and potassium (40K). Other gangue materials, sueh as highly siliceous cherts and jaspilites, escape detection because of their low activity. A dynamic trial of the shale detector at Mt Whaleback, using a large-volume (100 × 100 400 mm long) "Polyscin" Nal(TI) gamma-ray detector, demonstrated that as little as 20 tonne of ore on a conveyor belt (equivalent to partial truckloads of ore) can readily be monitored for shale content.

Jan 1, 1981

By Robert Hopler

Earthquakes, ground vibrations, seisms, or whatever you want to call the shaking of the earth, have been a fact of life throughout time. In spite of this, most people (except those unfortunate enough to live in seismicallyactive areas) have probably never felt this phenomenon, or if they have, only a very few times in their entire lifetime. However, when it does happen, nothing is more frightening than the sudden shaking of the earth beneath us - after all, we think of the ground we walk on as the unyielding, solid underpinning of our existence.

Jan 1, 2006

By LaTasha R. Swanson, Jennica L. Bellanca

Proximity detection systems (PDSs) for mobile machines have the potential to decrease injuries and fatalities. Early adopters of the technology have identified some challenges, which present an opportunity to explore and improve the integration of mobile PDSs in underground coal mines. The current research study applied the task-technology fit framework to investigate the fit between mobile PDS technology and mining relative to health and safety, from the perspective of leaders at two coal mines. Quantitative results from the study show that mine leaders evaluated mobile PDS favorably for training and ease of use, system feedback, user authorization and experience, and less favorably for safety, compatibility, task completion, and reliability. Qualitative results reveal specific task, mine, and system characteristics that may have influenced leaders’ evaluations. The study includes considerations and suggestions for safe technology integration

By LaTasha R. Swanson, Jennica L. Bellanca

Proximity detection systems (PDSs) for mobile machines have the potential to decrease injuries and fatalities. Early adopters of the technology have identified some challenges, which present an opportunity to explore and improve the integration of mobile PDSs in underground coal mines. The current research study applied the task-technology fit framework to investigate the fit between mobile PDS technology and mining relative to health and safety, from the perspective of leaders at two coal mines. Quantitative results from the study show that mine leaders evaluated mobile PDS favorably for training and ease of use, system feedback, user authorization and experience, and less favorably for safety, compatibility, task completion, and reliability. Qualitative results reveal specific task, mine, and system characteristics that may have influenced leaders’ evaluations. The study includes considerations and suggestions for safe technology integration

By S. McAlister

"Falcon Concentrators Inc. has developed a high capacity centrifuge for the recovery of fine, free gold as well as other metals and minerals which were previously thought to be unrecoverable by gravity means. Development started in the early 1980's and the first commercial operation was commissioned in 1986. Gold applications include scavenging conventional gravity and cyanidation circuit tailings, cleaning gravity concentrates, cleaning flotation concentrates to melting grade, scavenging flotation tailings, and placer mining. Recent development work by Falcon has expanded the applications scope of the centrifugal concentrator to include many minerals amenable to gravity concentration including iron, tin, industrial minerals, and hazardous wastes. This paper discusses this technology including its history, present applications, and future potential. OVERVIEW OF CENTRIFIJGAL CONCENTRATIONUsing centrifugal force to enhance the separation of materials by differential specific gravity has been researched for over a century. Many attempts have been made to concentrate minerals in high gravity fields. Patents were granted on this subject as early as 1891 (see Figure 1). Patenting activity continued into the 1920's and has been relatively quiet since. It is significant that no centrifugal system of gravity concentration has been broadly accepted by the mineral processing community until recently. Much of the world's reserve of mineral deposits which are amenable to conventional gravity concentration technology (coarse-grained) have been mined and therefore there is an increasing demand for technology which can economically recover the fine-grained gravity recoverable minerals in the remaining deposits. In addition, centrifugal concentration can play an increasing role in solving environmental problems by offering an inexpensive method of concentrating hazardous materials such as uranium, plutonium, mercury, lead, and other heavy metals. The overall cost of disposing of these substances safely can be drastically reduced if they are recovered into a concentrated form prior to disposal."

Jan 1, 1992

By P. S. G. Leon

One of the most difficult areas in concession contracts in resource-rich developing countries is achieving an equitable balance between the interests of investors, host states and, increasingly, mine and near mine communities. While some countries in the Andean region have resorted to outright or creeping expropriation of natural resource contracts under the guise of resource nationalism, others such as the Democratic Republic of the Congo (DRC), have claimed international best practice in the review (and setting aside) of important concession contracts.

Jan 1, 2011